2561658 has 32 divisors (see below), whose sum is σ = 5745600. Its totient is φ = 754560.

The previous prime is 2561653. The next prime is 2561659. The reversal of 2561658 is 8561652.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2561651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1918 + ... + 2966.

It is an arithmetic number, because the mean of its divisors is an integer number (179550).

2^2561658 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2561658, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2872800).

2561658 is an abundant number, since it is smaller than the sum of its proper divisors (3183942).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2561658 is a wasteful number, since it uses less digits than its factorization.

2561658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1102.

The product of its digits is 14400, while the sum is 33.

The square root of 2561658 is about 1600.5180411354. The cubic root of 2561658 is about 136.8276020703.

The spelling of 2561658 in words is "two million, five hundred sixty-one thousand, six hundred fifty-eight".